This invention is related to the catalytic treatment of heavy hydrocarbon streams containing asphaltenic material, metals, nitrogen compounds, and sulfur compounds. The heavy hydrocarbon stream is first hydrotreated in the presence of hydrogen with a suitable hydrotreating catalyst having specific properties to reduce the metals content and convert asphaltenes, nitrogen compounds, and sulfur compounds and at least a portion of the hydrotreated effluent is then catalytically cracked.
It is widely known that various organometallic compounds and asphaltenes are present in petroleum crude oils and other heavy petroleum hydrocarbon streams, such as petroleum hydrocarbon residua, hydrocarbon streams derived from tar sands, and hydrocarbon streams derived from coals. The most common metals found in such hydrocarbon streams are nickel, vanadium, and iron. Such metals are very harmful to various petroleum refining operations, such as hydrocracking, hydrodesulfurization, and catalytic cracking. The metals and asphaltenes cause interstitial plugging of the catalyst bed and reduced catalyst life. The various metal deposits on a catalyst tend to poison or deactivate the catalyst. Moreover, the asphaltenes tend to reduce the susceptibility of the hydrocarbons to desulfurization. If a catalyst, such as a desulfurization catalyst or a fluidized cracking catalyst, is exposed to a hydrocarbon fraction that contains metals and asphaltenes, the catalyst will become deactivated rapidly and will be subject to premature removal from the particular reactor and replacement by new catalyst.
Although processes for the hydrotreating of heavy hydrocarbon streams, including but not limited to heavy crudes, reduced crudes, and petroleum hydrocarbon residua, are known, the use of fixed-bed catalytic processes to convert such feedstocks without appreciable asphaltene precipitation and reactor plugging and with effective removal of metals and other contaminants, such as sulfur compounds and nitrogen compounds, are not too common. While the heavy portions of hydrocarbon streams once could be used as a low-quality fuel or as a source of asphaltic-type materials, the politics and economics of today require that such material be hydrotreated to remove environmental hazards therefrom and to obtain a greater proportion of usable products from such feeds.
It is well known that petroleum hydrocarbon streams can be hydrotreated, i.e., hydrodesulfurized, hydrodenitrogenated, and/or hydrocracked, in the presence of a catalyst comprising a hydrogenating component and a suitable support material, such as an alumina, an alumina-silica, or silica-alumina. The hydrogenating component comprises one or more metals from Group VI and/or Group VIII of the Periodic Table of Elements, such as the Periodic Table presented on page 628 of WEBSTER'S SEVENTH NEW COLLEGIATE DICTIONARY, G. & C. Merriam Company, Springfield, Mass., U.S.A. (1963). Such combinations of metals as cobalt and molybdenum, nickel and molybdenum, cobalt, nickel, and molybdenum, and nickel and tungsten have been found useful. For example, U.S. Pat. No. 3,340,180 teaches that heavy hydrocarbon streams containing sulfur, asphaltic materials, and metalliferous compounds as contaminants can be hydrotreated in the presence of a catalyst comprising such metal combination and an activated alumina having less than 5% of its pore volume that is in the form of pores having a radius of 0 Angstrom units [A] (0 nm) to 300 A. (30 nm) in pores larger than 100 A. (10 nm) radius and having less than 10% of said pore volume in pores larger than 80 A. (8 nm) radius.
U.S. Pat. No. 4,016,067 discloses that heavy hydrocarbon streams can be demetalated and desulfurized in a dual catalyst system in which the first catalyst comprises a Group VI metal and a Group VIII metal, preferably molybdenum and cobalt, composited with an alumina support having a demonstratable content of delta and/or theta alumina and has at least 60% of its pore volume in pores having a diameter of about 100 A. (10 nm) to 200 A. (20 nm), at least about 5% of the pore volume in pores greater than 500 A. (50 nm) in diameter, and a surface area of up to about 110 square meters per gram (m.sup.2 /gm) and in which the second catalyst comprises a similar hydrogenating component composited with a refractory base, preferably alumina, and has at least 50%, and preferably at least 60%, of its pore volume contributed by pores that have a diameter of 30 A. (3 nm) to 100 A. (10 nm) and a surface area of at least 150 m.sup.2 /gm.
U.S. Pat. No. 2,890,162 teaches that catalysts comprising active catalytic components on alumina and having a most frequent pore diameter of 60 A. (6 nm) to 400 A. (40 nm) and pores which may have diameters in excess of 1,000 A. (100 nm) are suitable for desulfurization, hydrocracking, hydroforming of naphthene hydrocarbons, alkylation, reforming of naphthas, isomerization of paraffins and the like, hydrogenation, dehydrogenation, and various types of hydrofining operations, and hydrocracking of residua and other asphalt-containing materials. It is suggested that suitable active components and promoters comprise a metal or a catalytic compound of various metals, molybdenum and chromium being among 35 listed metals.
U.K. Pat. No. 1,051,341 discloses a process for the hydrodealkylation of certain aromatics, which process employs a catalyst consisting of the oxides or sulfides of a Group VI metal supported on an alumina, having a porosity of 0.5 milliliters per gram (ml/gm) to 1.8 ml/gm and a surface area of 138 m.sup.2 /gm to 200 m.sup.2 /gm, at least 85% of the total porosity being due to pores having a diameter of 150 A. (15 nm) to 550 A. (55 nm).
U.S. Pat. Nos. 3,245,919 and 3,267,025 disclose hydrocarbon conversion processes, such as reforming, hydrocracking, hydrodesulfurization, isomerization, hydrogenation, and dehydrogenation, that employ a catalyst of a catalytic amount of a metal component selected from metals of Group VI and Group VIII, such as chromium, molybdenum, tungsten, iron, nickel, cobalt, and the platinum group metals, their compounds, and mixtures thereof, supported on gamma-alumina obtained by the drying and calcining of a boehmite alumina product and having a pore structure totalling at least about 0.5 cc/gm in pores larger than 80 A. (8 nm) in size.
U.S. Pat. No. 3,630,888 teaches the treatment of residuum hydrocarbon feeds in the presence of a catalyst comprising a promoter selected from the group consisting of the elements of Group VIB and Group VIII of the Periodic Table, oxides thereof, and combinations thereof, and a particulate catalytic agent of silica, alumina, and combinations thereof, having a total pore volume greater than 0.40 cubic centimeters per gram (cc/gm), which pore volume comprises micropores and access channels, the access channels being interstitially spaced through the structure of the micropores, a first portion of the access channels having diameters between about 100 A. (10 nm) and about 1,000 A. (100 nm), which first portion comprises 10% to 40% of the pore volume, and the remainder of the pore volume being micropores having diameters of less than 100 A. (10 nm), which remainder comprises 20% to 80% of the total pore volume.
U.S. Pat. No. 3,114,701, while pointing out that in hydrofining processes nitrogen compounds are removed from petroleum hydrocarbons in the presence of various catalysts generally comprising chromium and/or molybdenum oxides together with iron, cobalt, and/or nickel oxides on a porous oxide support, such as alumina or silica-alumina, discloses a hydrodenitrification process employing a catalyst containing large concentrations of nickel and molybdenum on a predominantly alumina carrier to treat hydrocarbon streams boiling at 180.degree. F. (82.degree. C.) to about 1,050.degree. F. (566.degree. C.).
U.S. Pat. No. 2,843,552 discloses that a catalyst containing chromia in an appreciable amount with alumina provides a very good attrition resistant catalyst, can have molybdenum oxide impregnated thereon, and can be used in reforming, desulfurization, and isomerization processes.
U.S. Pat. No. 2,577,823 teaches that hydrodesulfurization of heavy hydrocarbon fractions containing from 1% to 6.5% sulfur in the form of organic sulfur compounds, such as a reduced crude, can be conducted over a catalyst of chromium, molybdenum, and aluminum oxides, which catalyst is prepared by simultaneously precipitating the oxides of chromium and molybdenum on a preformed alumina slurry at a pH of 6 to 8.
U.S. Pat. No. 3,265,615 discloses a method for preparing a supported catalyst in which a catalyst carrier of high surface area, such as alumina, is impregnated with ammonium molybdate and then immersed in an aqueous solution of chromic sulfate, and the treated carrier is dried overnight and subsequently reduced by treatment with hydrogen at the following sequential temperatures: 550.degree. F. (288.degree. C.) for 1/2 hour; 750.degree. F. (399.degree. C.) for 1/2 hour; and 950.degree. F. (510.degree. C.) for 1/2 hour. The reduced material is sulfided and employed to hydrofine a heavy gas oil boiling from 650.degree. F. (343.degree. C.) to 930.degree. F. (499.degree. C.).
U.S. Pat. No. 3,956,105 discloses a process for hydrotreating petroleum hydrocarbon fractions, such as residual fuel oils, which process employs a catalyst comprising a Group VIB metal (chromium, molybdenum, tungsten), a Group VIII metal (nickel, cobalt) and a refractory inorganic oxide, which can be alumina, silica, zirconia, thoria, boria, chromia, magnesia, and composites thereof. The catalyst is prepared by dry mixing a finely divided Group VIB metal compound, a Group VIII metal compound, and a refractory inorganic oxide, peptizing the mixture and forming an extrudable dough, extruding, and calcining.
U.S. Pat. No. 3,640,817 discloses a two-stage process for treating asphaltene-containing hydrocarbons. Both catalysts in the process comprise one or more metallic components selected from the group consisting of molybdenum, tungsten, chromium, iron, cobalt, nickel, and the platinum group metals on a porous carrier material, such as alumina, silica, zirconia, magnesia, titania, and mixtures thereof, the first catalyst having more than 50% its macropore volume characterized by pores having a pore diameter that is greater than about 1,000 A. (100 nm) and the second catalyst having less than 50% of its macropore volume characterized by pores having a pore diameter that is greater than about 1,000 A. (100 nm).
U.S. Pat. No. 3,957,622 teaches a two-stage hydroconversion process for treating asphaltene-containing black oils. Desulfurization occurs in the first stage over a catalyst that has less than 50% of its macropore volume characterized by pores having a pore diameter greater than about 1,000 A. (100 nm). Accelerated conversion and desulfurization of the asphaltenic portion occur in the second stage over a catalyst having more than 50% of its macropore volume characterized by pores having a pore diameter that is greater than 1,000 A. (100 nm). Each catalyst comprises one or more metallic components selected from the group consisting of molybdenum, tungsten, chromium, iron, cobalt, nickel, the platinum group metals, and mixtures thereof on a support material of alumina, silica, zirconia, magnesia, titania, boria, strontia, hafnia, or mixtures thereof.
French Pat. No. 2,281,972 teaches the preparation of a catalyst comprising the oxides of cobalt, molybdenum, and/or nickel on a base of aluminum oxide and 3 to 15 wt.% chromium oxide and its use for the refining of hydrocarbon fractions, preferably for the hydrodesulfurization of fuel oils obtained by vacuum distillation or residual oils obtained by atmospheric distillation. The base can be prepared by coprecipitation of compounds of chromium and aluminum.
U.S. Pat. No. 3,162,596 teaches that, in an integrated process, a residual hydrocarbon oil containing metal contaminants (nickel and vanadium) is first hydrogenated either with a hydrogen donor diluent or over a catalyst having one or more hydrogenation promoting metals supported on a solid carrier exemplified by alumina or silica and then vacuum distilled to separate a heavy gas oil fraction containing reduced quantities of metals from an undistilled residue boiling primarily above about 1,100.degree. F. (593.degree. C.) and containing asphaltic material. The heavy gas oil fraction is subsequently catalytically cracked.
U.S. Pat. No. 3,180,820 discloses that a heavy hydrocarbon stock can be upgraded in a two-zone hydrodesulfurization process, wherein each zone employs a solid hydrogenation catalyst comprising one or more metals from Groups VB, VIB, and VIII of the Periodic Table of Elements. Either catalyst can be supported or unsupported. In a preferred embodiment, the first zone contains a supported catalyst in a fixed bed, slurry, or fluidized bed. The support of the supported catalyst is a porous refractory inorganic oxide carrier, including alumina, silica, zirconia, magnesia, titania, thoria, boria, strontia, hafnia, and complexes of two or more oxides, such as silica-alumina, silica-zirconia, silica-magnesia, alumina-titania, and silica-magnesia-zirconia, among others. The patent provides that the supported catalyst which is appropriate for use in the invention will have a surface area of about 50 m.sup.2 /gm to 700 m.sup.2 /gm, a pore diameter of about 20 A. (2 mm) to 600 A. (60 mm), and a pore volume of about 0.10 ml/gm to 20 ml/gm.
U.S. Pat. Nos. 3,977,961 and 3,985,684 disclose processes for the hydroconversion of heavy crudes and residua, which processes employ one or two catalysts, each of which comprises a Group VIB metal and/or a Group VIII metal on a refractory inorganic oxide, such as alumina, silica, zirconia, magnesia, boria, phosphate, titania, ceria, and thoria, can comprise a Group IVA metal, such as germanium, has a very high surface area and contains ultra-high pore volume. The first catalyst has at least about 20% of its total pore volume of absolute diameter within the range of about 100 A. (10 mm) to about 200 A. (20 mm), when the catalyst has a particle size diameter ranging up to 1/50 inch (0.051 cm), at least about 15% of its total pore volume of absolute diameter within the range of about 150 A. (15 nm) to about 250 A. (25 nm), when the catalyst has a particle size diameter ranging from about 1/50 inch (0.051 cm) to about 1/25 inch (0.102 cm), at least about 15% of its total pore volume of absolute diameter within the range of about 175 A. (17.5 nm) to about 275 A. (27.5 nm), when the catalyst has an average particle size diameter ranging from about 1/25 inch (0.102 cm) to about 1/8 inch (0.32 cm), a surface area of about 200 m.sup.2 /gm to about 600 m.sup.2 /gm, and a pore volume of about 0.8 cc/gm to about 3.0 cc/gm. The second catalyst has at least about 55% of its total pore volume of absolute diameter within the range of about 100 A. (10 nm) to about 200 A. (20 nm), less than 10% of its pore volume with pore diameters of 50 A- (5 nm-), less than about 25% of its total pore volume with pore diameters of 300 A+ (30 nm+), a surface area of about 200 m.sup.2 /gm to about 600 m.sup.2 /gm, and a pore volume of about 0.6 cc/gm to about 1.5 cc/gm. These patents teach also that the effluent from such processes may be sent to a catalytic cracking unit or a hydrocracking unit.
U.S. Pat. No. 4,054,508 discloses a process for demetallization and desulfurization of residual oil fractions, which process utilizes 2 catalysts in 3 zones. The oil is contacted in the first zone with a major portion of a first catalyst comprising a Group VIB metal and an iron group metal oxide composited with an alumina support, the first catalyst having at least 60% of its pore volume in pores of 100 A. (10 nm) to 200 A. (20 nm) diameter and at least about 5% of its pore volume in pores having a diameter greater than 500 A. (50 nm), in the second zone with the second catalyst comprising a Group VIB metal and an iron group metal oxide composited with an alumina support, the second catalyst having a surface area of at least 150 m.sup.2 /gm and at least 50% of its pore volume in pores with diameters of 30 A. (3 nm) to 100 A. (10 nm), and then in a third zone with a minor portion of the first catalyst.
U.S. Pat. No. 3,168,461 teaches the hydrotreating of a heavy metal-containing hydrocarbon oil prior to charging such hydrocarbon oil, or a fraction thereof, to a fluid catalytic cracking operation. Furthermore, the cracking catalyst in the fluid catalytic cracking operation is subjected to a demetallization treatment. This patent states that in the hydrotreating operation hydrogenation catalysts generally known in the art can be employed and that such catalysts contain catalytically active amounts of a hydrogenation-promoting metal, such as metals having atomic numbers of about 23 to 28, the Group VIII catalysts of the platinum and iron groups, molybdenum, tungsten, and combinations thereof. It further discloses that the metals are frequently disposed as inorganic components, for instance, oxides, sulfides, or other compounds, supported on a solid carrier exemplified by alumina or silica. The demetallization of the cracking catalyst includes sulfiding, sulfating, and chlorination.
Now there has been found and developed a process for hydrotreating a heavy hydrocarbon stream containing metals, asphaltenes, nitrogen compounds, and sulfur compounds, which process comprises (1) hydrotreating the heavy hydrocarbon stream in the presence of a catalyst that has special physical characteristics and a hydrogenating component containing molybdenum and chromium, and optionally cobalt, to produce a hydrotreated effluent and (2) catalytically cracking at least a portion of the hydrotreated effluent.